Internal combustion engine



May Z, 1939.

K. ZINNER INTERNAL COMBUSTION ENGINE l Filed March 27, 1956 2 .Sheets-Sheet l Jnran'or May 2, 1939. K. zlNNER INTERNAL COMBUSTION vENGINE Fileq March 27, v1956 2 sheets-sheet 2 Patented Mey 2, 1939 2,156,327

UNITED STATES PATENT OFFICE INTERNAL coMBUsTIoN ENGINE Karl Zinner, Dresden, Germany, assignor to Daimler-Benz Aktiengesellschaft, Stuttgart- Unterturkheim, Germany Application March 27, 1936, Serial No. 71,159 In Germany April 1, 1935 7 Claims. (Cl. 12s- 33) My invention relates to internal combustion shielded from direct impin'gement by the fuel, it engines and, more particularly,.to engines of the will not -be cooled by the.jet and will keep its type in which a jet of nel free from atomizing high temperature. Preferably, the heat accumuair is injected into a pre-combustion chamber lator' is formed by a partition provided in the communicating with the compression space of pre-combustion chamber near the bottom therethe cylinder. of. This partition is formed with a compact cen- The object of my invention is to provide a, trai portion surrounded byamultiplicity of com' machine of this type capable of being operated peretvely narrcw passages. The air flowing with a liquid fuel of a comparatively high igniv through these 'passages into the pre-combustion 1o tion temperature, such as tar oil. Previous exchamber and the burning gases flowing through lo perience has shown that it is extremely diicult the passages in the opposite direction enter into to obtain a reliable operation and a complete and en intimate heet exchange relation With -the emcient combustion of such fuel. The oxygen compact central Pclticn 0f the Partition Which and the temperature of the combustion air are alccllllllllcl'teS the heet teken 11p from the burning 15, of dominating importance for the prompt ignigases and then imparts it to the inowing air.

' tion of the fuel injected into the pre-combustion TllllS, a larger alIlOllnt 0f heet will be accumuchamber. As the oxygen content can be varied lated than it WOllld be DOSSible Withcllt Such a within but small limits, o, substantial improvepartition and the temperature of the combustion ment of the ignition and combustion may be ateil' will -be raised tc e higher limit than it would tained by a raise of temperature only. It has be POSSlble by the effect 0f the c OlnDI'eSSiOn alone- 20 been attempted prior to my invent-,ion to secure A vperforated disc serves to shield the compact proper ignition and combustion of fuels having central Dertien cf the Pertiticn from the direct a high ignition temperature by the insertion in impingelnent by the J'et 0f fuel- The Spacing 0f the pre-combustion chamber of heat accumulathe diSc fl'cm the Partition 2nd the dimensions tors which are not cooled and, therefore, become 0f the PeSSageS must be chosen in dependence 25 incandescent. These prior constructions, how-` 0f the conditions prevailing in any particular ever, have not proved satisfactory. It was found C95@- that the heat accumulator had to he kept at a Further Objects cf my invention will appear very high temperature to Secure proper ignition from the description of a preferred embodiment when the engine was running under small load following hereinafter and the features of novelty 30 and, as a resu1t, the injected fuel unpinging upon Will be pointed cut in the claims.

the high1y heated surface of the heat accumuia- In the drawings. Fis. 1 is e vertical section tor was cracked owing to the incomplete comthrough the upper P2"ril 0f an engine t0 Which hustion, particularly occurring under fu11 load my invention is availed: Fie, 2 is en exiel sec- 5 conditions, whereby'carbon was formed in the tien through e bushms fcrmme the nczzle-ccm- 35 pre-combustion chamber, munication between the pre-combustion chaml More particularly, it is an object, of my inven.. ber and the cylinder and provided with the heat tion to provide heat accumulating means in the accumulator and the Shielding disc; Fle 3 iS the pre-combustion chamber which may he kept at section teken elcns line 3-3 0f Fie. 2 showing a very high temperature without being hable to a plan view cf the shleldine disc: Fla 4 is the 40 crack the fue1 and' to form carbon, thereby sesection taken alone line 4'-4 of Fig. 3 illustrating curing a complete and very eicient combustion. the Plan VieW cf the heet accllmlllatcn and Fig- According to one feature of my invention, the 5 iS a Section Sllnilel t0 that 0f Flg 1 0f el Slightly heat accumulator interposed between the pre- Inlldifled embodiment in Which the bushing ferm- 5 combustion chamber proper and the nozzle esing the nozzle-communication and provided with 45 tablishing communication between the pre-comthe heat accumulator and the shielding disc is bustion chamber and th'e compression space of of a composite structure.

the cylinder is shielded from direct impingement With reference to Fig. 1, l' iS a cylinder block by the injected jet of fuel. The gases ovring of the engine. The cylinder proper is formed by past and through the heat accumulator enter a liner II inserted in the cylinder block and 50' into'intimate heat exchange relation therewith, forming a cooling jacket therewith. The piston whereby the combustion air compressed into the I2, the cylinder liner II and the cylinder head pre-combustion chamber will be heated to a very I3 mounted upon the cylinder block connue a high temperature thus securing prompt ignition compression space I4. of the injected fuel. As the heat accumulator is Suitable valves I5 are provided for the admis- 55 sion of air to and for the dischargeoi the burnt gases from the cylinder. The valv one of which only is visible in Fig. V1 are controlled in a. wellknown manner which need not be further described, the controlling means including a rocking lever I6 engaging the stein of the valve I5 and a. reciprocatory rod I1. v

The cylinder head is formed by a. casting providing for inlet and outlet conduits for the air and lthe exhaust controlled by the valves l5. These conduits are surrounded by hollow spaces through which a cooling medium is circulated.

Moreover, the cylinder head I3 is provided with a boring i8 traversing the cylinder head from a slanting upper face |9 to its lower face forming the top of the compression spaceolll. The upper part of this boring is of a larger diameter than the lower part andA accommodates a sleeve which is tightly tted into the boring and, in its turn, serves .to accommodate the fuel-injecting nozzle which need not be described in detail, as a description thereof will be given later with reference to Fig 5. It is sumcient to state that the fuel is fed tothe fuel-injecting valve generally designated by 2| through a pipe 22 under a high pressure sufficient to lift a spring-controlled valve needle, whereby the fuel will be injected into the central portion of the boring |8 and will be nely atomized without the use of any additional atomizing air. I

The lower reduced portion of the boring I8 is threaded and a bushing 23 is inserted therein. 'I'his bushing which is shown in Fig. 2 on an enlarged scale has a conical bottom 25 provided with a central opening 24 which constitutes a nozzle establishing a permanent communication between the compression space |4 lof the cylinder and the precombustion chamber formed'by the central and lower portion of the boring I8. The bushing is provided with an inner thread 26 and with an outer thread 21. The upper end of the bushing is left free from the outer thread and is adapted to tightly engage a corresponding cylindrical wall of the reduced lower portion of the boring |8. A peripheral recess 28 is provided in the bushing near the top thereof. This recess and the/wall just referred to dene a sealed annular heat insulating space which is so dimensioned that the bushing 23 will be kept at a higher temperature than the walls of the cylinder head.

For the purposes of my invention, I have inserted a heat accumulator inD the bushing 23, namely, between the pre-combustion chamber proper and the cylinder. This heat accumulator is formed by a cylindrical member provided with a compact central portion 29 surrounded Vby a.

multiplicity of comparatively narrow borings 30 which constitute passages or ducts for the combustion air entering and for the burning gases leaving the pre-combustion chamber. It will be noted from Fig. 4 that two concentric circular rows of borings 30 are provided. Owing to the large total surface of these borings, the air and the gases flowing therethrough will enter into an intimate heat exchange relation with the compact central portion 29. This portion is formed with ay lower tapered projection 3| which projects towards the nozzle 24 and together with the conical bottom face 25 of `the bushing deiines a passage having a gradually decreasing cross-section towards the nozzle.

The periphery of the cylindrical heat-accumulating member generally designated by 32, Fig. 4, is threaded and screwed into the bushing 23 and properly adjusted therein.

amasar In order to prevent the jet or spray of fuel issuing from the nozzle 2| from impinging directly upon the highly heated compact portion 29, I have interposed a suitable shield which, in the instant embodiment, is formed by a circular disc 33 provided with exterior threads and screwed into the bushing 23 so as to be slightly spaced from the heat accumulator 32. The disc 33 is provided with a circular row of passages or borings 34. It will be noted from Fig. 2 that the axial dimension of the heat accumulator 32 is a multiple of tha of the disc 33; that the diameter of the borings 34 is a multiple of that ot the borings 30 and that the number of the borings V3|| is a multiple of that of the borings 34.

The cylinder head is formed with a horizontal boring 35 which communicates with the boring I8 and serves'to accommodate a starting plug 36. This starting plug 36 which may be of a wellknown type and, therefore, need not be described in detail is provided with an incandescent wire 31 which projects into the pre-combustion chamber` and is so wound as to surround the .spray or jet of fuel without intersecting the same. For the purpose of starting the engine, current is supplied to the starting plug whereby the winding of wire 31 will be highly heated thus raising the temper'- ature of the combustion air to a degree securing proper ignition of the injected fuel. It is important that the winding of.wire 31 be made of so large a diameter als not to be impinged by the injected fuel. Otherwise, the wire would be 4Xquickly destroyed.

The operation of the machine is a's follows:

As soon as the engine has been started, the compact portion 29 of the heat accumulator will be heated to a high temperature. The air compressed by the piston |2 in the cylinder passes through the nozzle 24 and the borings 30 and 34 into the pre-combustionv chamber. In passing the borings 30 it is heated to a very high temperature higher than that caused by the compression alone. The spray of fuel injected by the nozzle 2| is immediately ignited and is partly burnt and partly vaporized in the precombustion chamber. As'a result, the pressure in the pre-combustion chamber is raised, whereby the mixture formed therein is driven out of the chamber through the borings 34 and 30 and through the nozzle 24 into the compression space |4 where it is mixed with the compressed air, thereby securing complete combustion. The burning gases passing through the borings 30 heat the compact portion 3| to a very high temperature. 'I'he disc 33 prevents the fuel particles from hitting directly the incandescent portion 23 and)y from forming carbon thereon.

'I'he embodiment illustrated in Fig. diifers but slightly from that afore-described. 'I'he plston 40, the cylinder 4| and the cylinder head 42 l conilne a compression space 43 which has a substantially larger volume than the pre-combustion chamber 44. 'Ihe cylinder head 42 is formed by a hollow casting through which a cooling medium is circulated.`

The pre-combustion chamber 44 is formed by a sleeve 45 which isin direct contact with the cooling medium and, for this purpose, is inserted thro h a shouldered boring 46 provided in a slan g upper wall 41 of the cylinder head. The shoulder of this boring is engaged by an upper flange 48 of the sleeve 45, a suitable gasket being interpsosed, and -is held in position by an annular nut 'I'he lower end of the sleeve 45 projects into a .of the upper part 54 and the lower part 55 which are attached to each other -by suitable screw threads. The part 56 has a conical bottom, similar to the bottom 25 provided with a centi'al nozzle 51 which establishes permanent communication between the pre-combustion chamber and thecompression space 43. The part 54, 55 of the bushing is provided with a thick bottom which constitutes the heat-accumulating member. This heat-accumulating member is of substantially,

the same structure as that described above, that is to say, it has a compact central portion'58 surrounded by two circular rows of narrow borings.

The portion 54 of the bushing is provided with an inner thread in which the shielding plate 59 is inserted. This shielding plate corresponds substantially to the shielding plate 33 and, therefore, need not be described in detail.

As in the above described embodiment, the boss 5| is formed'integral with a boss 60 traversed by a horizontal boring 6I communicating with the boring 32 and accommodating a starting plug 62. The incandescent wire 63v of the starting plug projects through a lateral boring 64 of the sleeve 45 into the pre-combustion chamber 44. The wire is so wound as to surround the jet or spray of the fuel without intersecting the same for the reason above explained.

Owing to the high temperature imparted to the air entering the pre-combustion chamber, the walls of this chamber will reach a very high temperature. Therefore, special precautions must be taken to avoid an overheating of the lower end of the vfuel-injecting nozzle. This lower end is designated by 55. I have found that its overheating may be successfully prevented by the interposition of an annular disc 65 of a material of high heat-conductivity, such as copper. Moreover, copper has the advantage of being comparatively pliant. Therefore, the annular disc 65 may serve the twofold purpose of serving l as a gasket preventing the highly heated combustion gases from passing up along the injecting nozzle and heating the same and of dissfpating the heat and conducting the same to the cooled sleeve 45.

The composite bushing 54, 56 is surrounded by an annular sealed insulating space 12.

'I'he fuel-injecting nozzle which need not be described in detail is pressed against the disc 65 by nuts 61. screwed upon bolts 68 attached to the cylinder head. The fuel is fed from a pump under pressure through a pipe 69 and enters through suitable conduits 10 an annular space surrounding the lower end of a spring-pressed injection valve 1I, which is lifted under thev pressure of said fuel against the action of its spring and admits the fuel into the pre-combustion chamber 44 in a ne spray.

My invention is capable of numerous modications and is not restricted to the details above described. Whilethe heat accumulator has been shown in the above embodiments as being separate from the bottom wall of the pre-combustion chamber, such as wall 55, it will be readily understood that it may be made vin one part therewith, if desired. f

Other modifications and changes in my invention as dened in the claims which follow will be apparent to those skilled in the art.

What I claim is:

l'. In an internal combustion engine, the combination comprising a cylinder space, a precombustion vchamber in permanent communication with said cylinder space, a fuel injecting nozzle opening into said precombustion chamber, a partition in said precombustion chamber arranged adjacent to said cylinder space and provided with a -center core portion which is of appreciable mass to accumulate heat and is surrounded by a multiplicity of narrowopenings, and a perforated disc interposed between said fuel injecting nozzle and said partition, spaced from but close to the latter and having a solid central portion arranged in line with said center core portion and adapted to shield the latter from direct impingement by the jet of fuel, the perforations in said disc surrounding the solid central portion being arranged substantially in line with said narrow openings.

2. In an internal combustion engine, the combination comprising a cylinder, a precombustion chamber, alpermanent communication between said cylinder andsaid precombustion chamber, a fuel injecting nozzle opening into said precombustion chamber, a partition in said precombustion chamber arranged adjacent to said communication, and provided with a multiplicity of bores and with a center core portion which is of appreciable mass to accumulate heat, and a perforated disc interposed between said fuel injecting nozzle-and said partition, spaced from but close to the latter and adapted to shield said compact central portion from direct impingement fromthe jet of fuel, the number of said bores being a multiple of the number of the perforations-of said disc and the diameter of said bores being smaller than the diameter of said perforations.

3. In an internal combustion engine, a cylinder, a precombustion chamber communicating therewith, said precombustion chamber consisting of relatively wide and narrow portions, said narrow portions being positioned between the wide portion of said precombustion chamber and the cylinder and thereby forming the connectionbetween the precombustion chamber and the cyl- "inder, a fuel injecting nozzle in the wide portion of the precombustion chamber, by means of which the fuel is injected without air into the narrow portion of the precombustion chamber, a solid core member surrounded by penetrating openings serving as heat accumulator and positioned inthe narrow portion of th'e precombustion chamber nearest the cylinder, and a perforated shielding'plate positioned at a distance from said core member and inside the narrow lportion of the precombustion chamber between the injection nozzle and said core member, the perforations in said shielding plate being positioned substantially outside of the fuel stream injected in the direction of the solid core member, whereby the shielding plate protects the core member, which serves as a heat accumulator, from direct impingement of the fuel injected from said nozzle, the thickness of said shielding plate being less than that of the solid core member.

4. In an internal combustion engine, a main combustion space, a precombustion chamber, an injection nozzle through which the fuel is injected without air into said precombustion chamber, an intervening wall between the precombustion chamber and the main' combustion space having a throttle opening therein, an intermediate partition in the precombustion chamber in front of said` wall, said partition having a plurality of penetrating passages surrounding a core' piece positioned before the throttle opening and serving as a heat accumulator, and a perforated shielding plate-positioned at a distance from the intermediate partition between the injecting nozzle and said intermediate partition, the perforations of said shielding plate being positioned ,substantially outside of the fuel stream injected in the direction of the core piece, whereby said shielding plate protects said core piece against a direct impact of the fuel injected from said nozzle.

5. In an internal combustion engine, a cylinder, a precombustion chamber, a fuel injecting nozzle through which the fuel is injected into the precombustion chamber without air, a throttling connection between said precombustion chamber and said cylinder which is positioned at that end of the precombustion chamber opposite the fuel injecting nozzle, a solid core member serving as a heat accumulator in the precombustion chamber on the side of said throttle connection, said Vsolid member` including surrounding'penetrating openings through which the collected air passing from the cylinder into the precombustion chamber must pass, and a perforated shielding plate spaced from but relatively near said solid memamasar ber. between the injection nomle and said solid member, the holes in said shielding plate beingv positioned substantially outside of the fuel stream injected in the direction ofthe fuel member, whereby the shielding plate protects the solid member serving as a heat accumulator against a direct impact `of the fuel' injected from the nozzle, the thickness of said shielding plate being less than that of said fuel member serving as a heataccumulator.

6. In-an internal combustion engine, the combination comprising a cylinder space, a precombustion chamber in permanent communication with said cylinder space, a fuel injecting nozzle opening into saidprecombustion chamber, a partition in said precombustion chamber arranged adjacent to said cylinder space and provided with a center core portion which is of appreciable mass to accumulate heat and is surrounded by a'multiplicity of narrow openings, and a perforated disc interposed between said fuel injecting nozzle and said partition, spaced from but close `to the latter and having a solid central portion`- arranged in line with said center vcore portion and adapted to shield the latterfrom direct impingement by the .iet of fuel.

7. In an internal combustion engine, the combination according to claim 6 wherein the said partition is of substantially greater thickness than the said perforated disc.

KARL ZINNER. 

